<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<button type="button" onclick="fun()" id="btn">按钮</button>
		<script type="text/javascript">
			var fun=function(){
				var btn=document.getElementById("btn")
				var text=btn.innerText;
				console.log(text);
				var textB="<b>"+text+"</b>";
				btn.innerText=textB; 
				//btn.innerHTML=textB;
			} 
		</script>
		
	</body>
</html>
